Coordinated deformation control technologies for the high sidewall—bottom transfixion zone of large underground hydro-powerhouses

It is imperative to understand the spatial and temporal coordination deformation mechanism and develop targeted deformation control technologies for high sidewall — bottom transfixion (HSBT) zones to guarantee the stability of rock surrounding underground hydro-powerhouses under complex geological conditions. In this study, the spatial and temporal coordinated deformation control of HSBT zones was addressed from the aspects of the deformation mechanism, failure characteristics, and control requirements, and some coordinated deformation control technologies were proposed. On this basis, a case study was conducted on the deformation control of the HSBT zone of the underground powerhouse at the Wudongde hydropower station, China. The results showed that the relationship between excavation and support, and the mismatch of deformation and support of the surrounding rock mass in the HSBT zone of underground caverns with a large span and high in-situ stress can be appropriately handled. The solution requires proper excavation and construction procedures, fine blasting control, composite and timely support, and real-time monitoring and dynamic feedback. The technologies proposed in this study will ensure the safe, high-quality, and orderly construction of the Baihetan and Wudongde underground caverns, and can be applied to other similar projects.